chrome://flags/#enable-pointer-lock-options
chrome://flags/#exo-pointer-lock
据说84版本之后会失效
已知问题（生肉）：
This implementation is imperfect for several reasons:
– Historically pointer lock was only available for Arc as part of
android’s “pointer capture” (which in wayland terms is a combination
of locking, relative motion, and cursor hiding). This CL does not
change that behaviour, meaning locking will also hide the cursor.
– We do not implement UI support for unlocking the pointer. Users
assume responsibility for malicious applications if they enable the
flag. Note that users can force the pointer to unlock via alt+tab
or by bringing up the launcher.
– We do not fix the underlying limitations in aura w.r.t. relative
motion. Applications which request relative motion without locking
the pointer will be sent inaccurate information if the pointer hits
a barrier. This is a preexisting limitation and was not fixed by
this CL.
For this reason it will only be available behind a flag.
来源：
https://bugs.chromium.org/p/chromium/issues/detail?id=927521#c34
https://chromium.googlesource.com/chromium/src/+/e9a6744f19342093b0d62ade4892092928b69980